I had a dream about them Friday night, and thought, “Well, they haven’t been around lately, so I should blog about my experiences with them”. But, right on cue, they came back Sunday, so it’s even more relevant.
I only lived in the Bay Area for about 2 years, but I didn’t feel an earthquake in that time. There were two decent sized ones during my time there, a 5.2 in Napa (which I slept through, living in Richmond at the time), and a 4.4 in San Jose (which I was out of town for, and probably wouldn’t have felt it anyway).
When I moved to Reno in 2002, I didn’t think anything of earthquakes, though apparently Nevada is the #3 state in the union for earthquake occurrence (the other two are California and Alaska). In 2005, there was a 4.8 just outside Truckee. It was apparently enough to wake me up, but I didn’t realize that was the reason I had woken up (I put 2 and 2 together later in the day). After the news surrounding that, I found the University of Nevada’s Nevada Broadcast of Earthquakes web page. This is the information that feeds into the <a href=http://quake.usgs.gov/recenteqs/latest.htm”>USGS</a> for Nevada and Eastern California earthquakes. At the time, I was curious where exactly the epicenter of the earthquake (and its aftershocks) was. The NBE site didn’t have Google Maps links at the time, and while I could throw the co-ordinates directly into Google Maps, it was cumbersome. I used that as an excuse to make my first Google Maps application, a map of all earthquakes listed by UNR.
Now, note the “North Lake Tahoe/Truckee” link in my app. There are no earthquakes in that area. That is the “normal” mode of operation for an earthquake on a previously inactive fault: main quake happens, aftershocks happen for a few days/weeks/months later, but eventually die out.
On February 21 of this year, a 6.0 earthquake hit Wells, Nevada, a small town about 400 miles east of Reno. To this date, a few aftershocks have been happening per day, though very few have been over 3.0. However, a peculiar thing happened just after the Wells earthquake. Small (less than 2.0) earthquakes began happening around Mogul, a suburb northwest of Reno (again, 400 miles away). These were basically impossible to feel unless you were very close to the epicenters. (For reference: I live about 10 miles away from Mogul, and I work about 15 miles away.) They were small, but the trend was growing, both in number per day and magnitude.
There were a few 3s in the next few months, but I didn’t feel any of them, due to either sleeping through them, or being at work when they happened. I was rather frustrated and excited to feel one, as it’s one of the few natural disasters I haven’t experienced yet. Sounds a bit odd, yes, but I wanted to feel one, dammit.
On April 24, I was walking down the hall at work when a coworker said, “Did you feel that?” “No?” “That might have been an earthquake.” Sure enough, we checked the USGS a few minutes later, and it was a 4.2. Barely feelable in the South Meadows (and not feelable at all to some, *ahem*), but must have rattled a few things up in the Northwest.
That night, I was just getting ready to go to bed, when I felt a “thump”. I can’t find the event to grab the magnitude, but it was probably around 3.5. I did go online to check the report and talk on IRC about it, though:
2008-04-25 01:51:54 <%fo0bar> woot! I finally felt an earthquake!
2008-04-25 01:52:01 <%fo0bar> … it was quite disappointing
2008-04-25 01:55:26 <%fo0bar> the best I could describe it was if I was in a mobile home, and somebody kicked the wall
2008-04-25 01:55:46 <%fo0bar> a single side motion and some associated creaking
I went to bed, and was woken up by another mid-3 earthquake sometime after 6AM. There were a handful of 3s throughout the day, as we were following the news at work. Oh, let me clarify: these are just the 3s I’ve been talking about. By this point, there were over 100 earthquakes per day happening in Mogul (yes, really, 100), but most of them were 0s, 1s and some 2s. The technical term is and earthquake “swarm”. The following conversation after I got home sums up the day:
2008-04-25 18:51:01 <%fo0bar> damn, a 3.6 hit while I was driving home
2008-04-25 19:28:26 <%fo0bar> the city emergency management office held a press conference today. unfortunately, “freak the fuck out” wasn’t in their list of recommendations
2008-04-25 19:30:51 <%Screwtape> fo0bar: It seems earthquakes are being observed more and more frequently in your location. Do you think they’re preparing for an invasion?
2008-04-25 19:31:29 <%fo0bar> Screwtape: apparently we’ve infiltrated their ranks, and will know soon
2008-04-25 19:34:27 <%fo0bar> what’s a little scary is there wasn’t one big earthquake and a lot of smaller earthquakes. the little ones started happening a few weeks ago, with one or two 3s or 4s per day. this increases the chances that they could be foreshocks, with a larger quake coming
2008-04-25 19:35:22 <%fo0bar> the chance of a large quake happening is still between “immediately” and “never”, but the pattern puts it closer to the “immediately” side
2008-04-25 19:35:51 <%fo0bar> also, “foreshock” is a cool word
2008-04-25 19:36:03 <%fo0bar> it’s like foreplay, but without the chance for happy ending
[The politically incorrect humor goes on for a little while longer. Suffice it to say, it involved race stereotypes and Blondie references.]
Throughout the evening, a few more earthquakes happened. At about 10PM, I decided to go into work to work on Finnix for a bit (lots of computers available at work makes for good Finnix testing). At 11:40PM, a 4.7 hit that “felt” significantly larger than anything previously felt. I was in the systems/storage room at work when it hit, and equipment and racks were swaying around for a few seconds (even though the earthquake itself just felt like 2 “thumps”). Again, this was 15 miles away, and probably felt even more impressive if I were at home, or even closer to the epicenter.
The quake caused some minor damage, but nobody was injured. It did make the national news cycle because, well, Reno doesn’t normally get earthquakes.
After the 4.7, the swarm continued, but quickly died down from hundreds of quakes per day down to dozens, then just a few tiny ones by the end of May. Looking back, you could analyze the activity as a swarm that built up foreshocks into the 4.7 “main” shock. I went on with my life, with a little caveat. That is, it’s spring in Nevada, which means high winds. That, combined with moving into a new apartment with its own little settlings and creaks, meant every time a “thump” hit the side of the apartment, I would think, “wait, was that an earthquake?”
Which brings me to this weekend. Friday night, I had a dream involving earthquakes. I don’t remember what it was about, but I remember them being prominent in it. I was up late Saturday night/Sunday morning, and at about 3:15AM, I felt a thump hit the house. “Was that wind, or an earthquake?” I thought, and made a note to check UNR/USGS in a few minutes. Sure enough, it was a 3.2. At this point, let me remind you that every earthquake I’d felt until that point had also been “thumps”. It definitely wasn’t like the movies where you’re swaying back and forth, and there was definitely no rumbling. Just “thump” (or sometimes “thumpthump”), and then stuff inside the room would sway once or so. The thumps would definitely be harder or softer depending on the magnitude, but they were very short events.
Anyway, I thought it was a nice little anomaly for an otherwise “ended” swarm, and went to bed. Sunday morning I got up, but was still in bed in the “don’t wanna start the day” pose, when the room started shaking. And shaking. For a good 3 seconds, I could feel the building being pushed back and forth. I got up and grabbed the laptop, and started going to UNR to look at the webcam, which is available nearly instantly, as opposed to the automatically-generated reports, which take a good 10 minutes to come in. However, about 2 minutes after the first earthquake, it started shaking again, this time harder and for a good 5 seconds (which of course felt a lot longer). No damage, but it was definitely… different.
My mind linked “more shaking time” with “bigger” and hence “more magnitude”, and I guessed 4.2 and 4.8 respectively. I was disappointed when the final word came in: 3.6 and 3.9. Still, they were more impressive; closer to what I expected as “earthquakes” before all of this.
I don’t know if this is indicative of a new swarm, but there have been more tiny earthquakes in Mogul today than before this weekend. I haven’t been able to feel any of them from my home yet, though.